Trikkala Sub Clover

Trikkala is a white seeded mid maturing sub clover variety that displays excellent tolerance of waterlogging. It is suited to medium to heavy acidic soils receiving a minimum 450mm/year rainfall. Trikkala is performs well on flood plains, and in irrigated environments. It has very low levels of hardseed but shows good winter and early spring vigour.

Limitations

Shallow-rooted, so unable to capture deeper soil moisture and susceptible to premature death in dry springs.

Some older cultivars have high oestrogen levels contributing to ewe infertility.

Plant Description

A prostrate self-regenerating annual pasture legume tolerant of waterlogging and heavy grazing that grows from autumn through to spring and buries its burrs.

Pasture type and use

Suited to permanent and semi permanent pastures and to crop rotations where cropping is infrequent. Other subspecies (subterraneum and brachycalycinum) are better suited to soils not prone to waterlogging.

Where it grows

Rainfall: Adapted to winter-dominant rainfall area of southern Australia with annual rainfall 425 -1200 mm. Mid season varieties suited to medium rainfall zone, later flowering varieties suited to higher rainfall zone. Can also be grown under irrigation.

Inoculation: Goldstrike treated. The use of Goldstike XLR8 seed treatement is recommended to reduce damage from insects at seedling stages. Can be biologically fix 25kg nitrogen/tonne of herbage dry matter.

Management

Grazing/cutting: Thrives under set stocking and can be grazed moderately hard while flowering. Likely to be shaded out from more erect plants under lax grazing. Can be cut for hay.

Ability to spread: Slow spread from site of sowing. Can spread by burrs attaching to wool.

Weed potential: Its slow rate of spread, its preference for moderate-high fertility soils and specific rhizobia requirement gives it low potential as an environmental weed. It is readily controlled by a range of broadleaf herbicides within crop.

Major pests: Red legged earth mite is a major pest, particularly at plant establishment, where it can kill emerging seedlings, but also causes damage in spring. Timeritel has proved an effective means of control. Lucerne flea and blue green aphids can also cause damage in spring. Refer to chemical labels for suitability and recommended rates for insecticides.

Major diseases: Some cultivars are susceptible to the foliar disease clover scorch (Kabatiella caulivora), found in high rainfall, humid areas. Other foliar diseases in higher rainfall areas include leaf rust (Uromyces trifolii-repentis), powdery mildew (Erysiphe polygonii) and cercospora leafspot (Cercospora zebrina). Several root rots can attack subterranean clover, causing most damage to emerging seedlings and young plants. They include Phytophthora clandestina, Fusarium avanaceum, Pythium irregulare and Rhizoctonia solanii.

Herbicide susceptibility: Refer to chemical labels for suitability and recommended rates for herbicides registered for use on subterranean clover.

Animal production

Feeding value: Excellent as green feed with in vitro digestibility in the order of 70% and crude protein over 20% until mid-flowering. Quality reduces once plants hay off. Dry herbage feeding value over summer is less than maintenance value (often < 50% in vitro digestibility) although animals may be able to obtain sufficient energy and protein by digging up seed burrs.

Palatability: Readily consumed by livestock, either as green or dry feed.

Production potential: Vigorous seedlings provide good early season production. Later flowering varieties capable of more than 10 t/ha annual production in long season environments.

Livestock disorders/toxicity: Some older varieties of subterranean clover contain high levels of phyto-oestrogens, which can affect the sheep reproductive system. The most active isoflavone is formononetin, which can cause a decline in ewe fertility. Two other isoflavones, genistein and biochanin A, are also present in all subterranean clover varieties, but these have less impact. If ewes are mated when they are grazing green, potent subterranean clover their reproductive performance can be temporarily impaired. Continued exposure over several years to high levels of formononetin can lead to permanent infertility. Ram fertility is not affected. Formononetin is present in subterranean clover only while the pasture is green. However, hay produced from oestrogenic varieties can be almost as potent as green pastures. Formononetin levels drop away during late flowering. Generally, dry subterranean clover pastures that result from normal haying-off are not oestrogenic. However, if there is a very early finish to retain some potency in the dry state. All recently released varieties have low formononetin levels. There have been isolated reports of cattle bloat on very clover-dominant subterranean clover pastures.